1. Field of the Invention
The present invention relates to a zoom lens. In addition, the present invention relates to a camera that provides the same. In particular, the present invention relates to a zoom lens having a photographable angle of view equal to or greater than 70°, a brightness, and a high resolution that can be applied to a video camera, a digital camera, or the like. In addition, the present invention relates to a camera providing the same.
2. Description of Related Art
In recent years, a zoom lens having a total angle of view of about 60° at the wide-angle end and a zoom ratio of about 3 have dominated digital cameras for general users.
In contrast, in the case of digital cameras that target high-end users, a zoom lens is required having a focal length range from the wide-angle end to the telephoto end that is large, a high zoom ratio, and a large aperture. In addition, the pixel pitch of the digital camera becomes increasingly fine to attain a high resolution. Accompanying this, a high image quality is required in the zoom lens as well.
In response to these requirements, Japanese Unexamined Patent Application, First Publication, No. 2003-255228 (pages 9 to 16; FIGS. 1 to 4), for example, discloses a five-group zoom lens system, in which the refractive power of the lens group is, in order from the object side, a positive, negative, positive, negative, positive type, and in which the zoom ratio is from approximately 5 to 10 times.
However, the conventional zoom lens has the following problems.
In the technology disclosed in the above-cited document, the third lens group is configured including a simple positive lens and a cemented positive lens in which a negative lens and a positive lens are bonded together, and the diameter of the bundle of rays in proximity to the third lens group becomes large. Thus, the aberration that occurs at the third lens group easily becomes large. In addition, the refractive power of each of the lenses becomes strong, and the sensitivity to eccentricity between each of the lenses of the third lens group becomes high. In addition, when changing the magnification from the wide-angle end to telephoto end, the second lens group moves towards the object side, and thus the width of movement of the third lens group is limited. Thus, the refractive power of the third lens group must be made strong. In addition, the refractive power is concentrated in the positive lens on the object side, and thus the sensitivity to eccentricity becomes high. In addition, the fifth lens group is formed by a cemented lens, and thus the off-axial correction of aberration is not sufficient, and the image quality cannot be said to be high.
In consideration of the problems described above, it is an object of the present invention to provide a zoom lens having an advantageous aberration correction in response to high resolution, or a zoom lens having a small sensitivity to eccentricity and is easy to manufacture.